Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, MD 20982-4435.
Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, MD 20982-4435
eNeuro. 2021 Apr 12;8(2). doi: 10.1523/ENEURO.0395-20.2020. Print 2021 Mar-Apr.
What role does color play in the neural representation of complex shapes? We approached the question by measuring color responses of face-selective neurons, using fMRI-guided microelectrode recording of the middle and anterior face patches of inferior temporal cortex (IT) in rhesus macaques. Face-selective cells responded weakly to pure color (equiluminant) photographs of faces. But many of the cells nonetheless showed a bias for warm colors when assessed using images that preserved the luminance contrast relationships of the original photographs. This bias was also found for non-face-selective neurons. Fourier analysis uncovered two components: the first harmonic, accounting for most of the tuning, was biased toward reddish colors, corresponding to the L>M pole of the L-M cardinal axis. The second harmonic showed a bias for modulation between blue and yellow colors axis, corresponding to the S-cone axis. To test what role face-selective cells play in behavior, we related the information content of the neural population with the distribution of face colors. The analyses show that face-selective cells are not optimally tuned to discriminate face colors, but are consistent with the idea that face-selective cells contribute selectively to processing the green-red contrast of faces. The research supports the hypothesis that color-specific information related to the discrimination of objects, including faces, is handled by neural circuits that are independent of shape-selective cortex, as captured by the multistage parallel processing framework of IT (Lafer-Sousa and Conway, 2013).
颜色在复杂形状的神经表示中扮演什么角色？我们通过测量面孔选择性神经元的颜色反应来解决这个问题，使用猕猴下颞叶皮质（IT）中部和前部面区的 fMRI 引导微电极记录。面孔选择性细胞对纯颜色（等亮度）面孔照片的反应较弱。但是，当使用保留原始照片亮度对比度关系的图像评估时，许多细胞仍然表现出对暖色调的偏好。这种偏好也存在于非面孔选择性神经元中。傅里叶分析揭示了两个组成部分：第一个谐波，占大部分调谐，偏向于红颜色，对应于 L-M 主轴的 L>M 极。第二个谐波显示出在蓝黄色调之间调制的偏好，对应于 S-锥体轴。为了测试面孔选择性细胞在行为中的作用，我们将神经群体的信息内容与面孔颜色的分布相关联。分析表明，面孔选择性细胞不能很好地调谐以区分面孔颜色，但与这样的想法一致，即面孔选择性细胞选择性地有助于处理面孔的绿-红对比度。该研究支持了这样一种假设，即与物体（包括面孔）的区分相关的特定颜色信息是由与形状选择性皮层独立的神经回路处理的，这与 IT 的多阶段并行处理框架（Lafer-Sousa 和 Conway，2013）相吻合。
